Common mode noise takes the form of high frequency transient spikes that have a path to ground, and may be caused by, e.g., lightning strikes, power outages, and power transitions in other large equipment on the same power line. In electric motor systems, these common mode line transients can cause high currents in motor phase leads which can stress the power module and even cause it to fail. More specifically, during surge and ring wave transients, particularly line to ground transients, the inherent capacitance between the motor windings and the stator can cause high currents to flow in the outputs of a power inverter component of the power module, and these high currents can stress and damage the power output stage.
In larger drives in which the motor controls are not mounted to the electric motors, inductors have been used between the controls and the motors to filter the output power in order to reduce stress on the motors resulting from pulse width modulation edges and to reduce electromagnetic interference (EMI) from the motor leads. However, these inductors are not integrated and therefore require additional space, labor, and cost to install, and are subject to saturation at the high currents levels that occur during transients.
This background discussion is intended to provide information related to the present invention which is not necessarily prior art.